Men taking virologically suppressive ART have undetectable HIV in their pre-ejaculatory fluid

HIV is undetectable in the pre-ejaculatory fluid of men taking suppressive antiretroviral therapy, investigators from the United States report in the online edition of AIDS. Approximately a fifth of men with an undetectable viral load in their blood had low-level HIV replication in their semen, but none were shedding virus in pre-ejaculate.

“Our study provides the first evidence that pre-ejaculatory sexual secretions in men on [ART], unlike those from untreated men, do not contain detectable HIV,” comment the investigators.

There is now overwhelming evidence that men and women who are taking stable ART that suppresses HIV in blood to undetectable levels are extremely unlikely to transmit the virus to their sexual partners. However, persistent HIV replication has been detected in the semen of men taking treatment that suppresses viral load in blood.


detectable viral load

When viral load is detectable, this indicates that HIV is replicating in the body. If the person is taking HIV treatment but their viral load is detectable, the treatment is not working properly. There may still be a risk of HIV transmission to sexual partners.


Viral shedding refers to the expulsion and release of virus progeny (offspring such as competent particles, virions, etc.) following replication. In HIV this process occurs in the semen, the vaginal secretions and other bodily fluids, making those fluids more infectious.


The process of viral multiplication or reproduction. Viruses cannot replicate without the machinery and metabolism of cells (human cells, in the case of HIV), which is why viruses infect cells.

herpes simplex virus (HSV)

A viral infection which may cause sores around the mouth or genitals.


Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

HIV has been detected in the pre-ejaculatory fluid – colloquially called pre-cum – of HIV-infected men not on ART and also in pre-ejaculatory samples obtained from ART-exposed monkeys. Pre-ejaculate is thought to be a possible source of HIV transmission.

Investigators in Boston wanted to see if HIV-replication persists in pre-ejaculatory fluid in the context of treatment that suppresses viral load in blood and also to establish if there is a relationship between detectable viral load in semen and viral shedding in pre-ejaculate.

Their study sample comprised 60 men. All were sexually active and had been taking a stable antiretroviral regimen for at least three months.

Samples of pre-ejaculate, semen and blood were provided for viral load quantification. The men were also screened for urethral sexually transmitted infections (STIs), urethritis and HSV infections.

Eight of the men had detectable viral load in their blood (range, 80-640,000 copies/ml) and were excluded from the principal analysis.

The remaining 52 men all had blood viral load below the limit of detection (40 copies/ml). Their median age was 43 years, median CD4 cell count was 518 cells/mm3, 96% reported sex with other men, and 44% said they had had insertive unprotected anal sex within the past three months. None of the patients had a bacterial urethral STI, one had urethritis and one was shedding HSV-2 in semen.

Four of the men with detectable HIV in their blood were also shedding virus in their semen, viral load ranging between 40 and 96,000 copies/ml. One man in this group also had detectable virus in his pre-ejaculate (2,400 copies/ml).

Of the 52 men with undetectable viral load in their blood, ten (19%) had low level HIV replication in their semen (59 to 800 copies/ml). However, none had virus in their pre-ejaculatory fluid.

Both the patients with urethritis and the individual with seminal HSV-2 both had detectable HIV in their semen.

“Although HIV-1 RNA was detected in semen of men on stable ART with undetectable blood viral load, it was not detected in pre-ejaculatory secretions,” conclude the authors. “These data indicate that pre-ejaculatory fluid may not contribute to HIV transmission in men on ART, at least in men without genital infections.”


Politch JA et al. HIV-1 in pre-ejaculatory secretions from HIV-1 infected me on suppressive ART. AIDS, online edition. DOI: 10.1097/QAD. 000000000001130 (2016).